[ithacaartist]

A pic of grips from my Mauser Parabellum 29/70...

These original grip panels have two steel pins, using an approach that locates the pins in an area that will stand up to the stress of firing, as well as requiring no extra work to install a pin in the frame. They are not quite round cross section on their ends, and may have been filed to fit. Epoxy is on the scene, as well, and I suspect that it is not original.

The Erma KGP series uses the pin-in-frame concept. The successful one is the walnut type, a hole in the flat back side of the scale, in very sturdy surroundings. Their failure is their engineering of the index pin's accommodation in their plastic grips. The classic breakout has occurred--as you can see--kind of the equivalent of the damage to the wood grip, but expressed in plastic. All that resisted the forces of firing was a wall circle of styrene.

Alvin, the profile of the back of the grip is simple, yes, but it must be executed precisely!